Cammed firing pin



p 1957 E. A. HUMPHREY 2,

CAMMED FIRING PIN Filed Oct. 13, 1954 3 Sheets-Sheet 2 4 IN V EN TOR.

E dwnrd A- HLIH'LPl'lLEy p 10, 1957 E. A. HUMPHREY 2,805,604

CAMMED FIRING PIN Filed Oct. 15, 1954 3 Sheets-Sheet 5 INVENTOR. E dwur d A Humphrey JFTQRNEYE States Patent Ofifice 2,805,604 Patented Sept. 10, 1957 CAMMED Frame PIN Edward A. Humphrey, Springfield, Mass, assignor to the United States of America as represented by the Secretary of the Army Application October 13, 1954, Serial No. 462,123

3 Claims. (Cl. 89-l35) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

My invention relates to automatic revolver-type weapons and more particularly to a positively retractable electrically-conductive firing pin therefor.

The usual automatic revolver-type weapon comprises a recoil unit including a barrel and having a rotatably disposed drum with cartridge chambers and corresponding index rollers for serial rotation of the chambers to a firing station in axial alignment with the barrel.

An actuator axially slidable with respect to the recoil unit is provided with a groove for guiding the rollers including a straight portion with accelerating and decelerating portions oppositely curving therefrom, and a switching device to alternately connect the curved portions with the straight portion. The actuator is spring-biased to a battery position for engagement of the straight portion with one of the rollers to retain the corresponding chamher in the firing station for discharge of the cartridge therein. In the battery position, the accelerating portion is connected to the straight portion.

The actuator is operated in a rearward stroke responsive to the discharge with the straight portion of the groove engaging the one roller and during the continuation of the rearward stroke the accelerating portion engages the one roller to rotate the drum and convey the chamber including the discharged cartridge case from the firing station. At the end of the rearward stroke, while the drum continues to rotate, a switching device connects the decelerating portion to the straight portion and, when the actuator moves in the forward stroke, the succeeding roller is conveyed into contact with the decelerating curved portion to stop rotation of the drum. In the latter portion of the forward stroke, the straight portion engages the succeeding roller and a the end of the forward stroke the switching device reconnects the accelerating portion with the straight portion.

The weapon herein described is constructed for firing a cartridge with the primer thereof recessed in the base. A firing pin of the weapon is insulated, and spring-biased from a pedestal to a normal position for contact with the primer and the cartridge is fired by an electrical impulse transmitted by the firing pin to the primer. In the usual Weapon, the end of the firing pin is rounded for retraction thereof by engagement with the base of a cartridge rotated through the firing station. The electrical impulse to the firing pin is controlled by a knife switch disposed between the actuator and the recoil unit and connected to close as the actuator returns to battery position.

The succeeding chamber arrives at the firing station and the firing pin returns to normal position to conduct current to the primer as the straight portion of the actuator curve engages the corresponding roller and, therefore, there is an appreciable interval of the actuator forward stroke between the return of the actuator to the normal position and the time the knife switch closes.

During this interval, stray electric currents in the weapon may be transmitted by the firing pin to prematurely discharge the cartridge. Also, firing pins of the type described above have been known to fail by interference with cartridges due to adverse accumulation of tolerances in the recoil unit.

Such failures may be eliminated by providing the weapon with a firing mechanism including a device constructed to retract the firing pin during a portion of the actuator rearward stroke before the drum is rotated and to permit the firing pin to return to the normal position during a comparable portion of the actuator forward stroke after rotation of the drum is completed.

Such a device would eliminate interference between the firing pin and the cartridges and would also reduce the period of the forward actuator stroke in which stray electric currents could discharge cartridges chambered in the firing position.

Several types of electrically-conducting firing pins have been devised with positively actuated separate mechanisms for retracting the firing pins but these mechanisms have been spring-biased for forward return of the firing pin to the normal position. While such an arrangement would reduce the portion of the stroke in which the stray currents can discharge a cartridge in the firing position, the action of such a spring-biased mechanism is neither positive enough not fast enough for present rapid fire weapons.

It is an object of my invention, therefore, to provide such a weapon with an electrically-conductive firing pin that is axially operable independently of the rotation of the chambers of the weapon.

Another object of my invention is to provide such a weapon with a firing pin having a control mechanism that is positively operable both forwardly and rearwardly.

In carrying out my invention, an electrically-conductive firing pin including a tip and a body is disposed in a pedestal of the recoil unit with the tip and the body, respectively, projecting through separate carriage and clutch ends of a cylindrical member concentric therewith. The ends include corresponding axial teeth in rneshed relation for simultaneous rotation about the firing pin.

Flanges of the tip and body, respectively, are disposed within the member and a spring is compressed between the flanges to maintain electrical connection therebetween and to bias the tip and the carriage end forwardly. The tip projects through a forward wall of the pedestal to engage the primer of a cartridge chambered in the firing station of the weapon.

A diametrical groove is formed on the carriage end for engagement with a corresponding knife edge projection on the inner surface of the forward wall and the clutch end of the cylindrical member is provided with a squared boss concentric with the firing pin for engagement with a link. The tip and the remainder of the firing pin are separately inclosed in moulded material for electrical insulation from the cylindrical member and the anvil.

A double-acting cam track is provided on the actuator and a follower slidable in the recoil unit is yoked to the link for rotation of the cylindrical member to operate the firing pin tip rearwardly and forwardly responsive to operation of the actuator.

Accumulation of tolerances on the assembly of the drum in the recoil unit and in the cartridges is compensated by the compression spring.

For a more complete understanding of my invention, reference is made to the following description and the accompanying drawings in which:

Fig. l is a cross-sectioned partial elevational view of a weapon incorporating my invention with the tip of the firing pin in firing position;

Fig. 2 is an enlarged view similar to Fig. 1 with the tip in retracted position; i

' tion.

Fig. 3 is. n enlarged. view of the firing p em ly with the firing pin tip in retracted position;

Fig. 4 is a view along the line 44 of Fig. 1;

Fig.5 is a view along the line 55 of Fig. 4; and

Fig. 6 is an exploded view of the firing pin insert.

Accordingly, an automatic weapon 12 includes a receiver 14' with a recoil unit 16 and an actuator 18 slidably disposed thereon for respective axial reciprocation. Re.- coil unit: 16 includes a pedestal 20 and a cartridge drum 22 is rotatable on a shaft 24 journaled in pedestal 20.

Drum 22 is provided with cartridge chambers and corresponding radially axised index rollers, such as chamber 26'and roller 28:. Actuator 18 is biased to a battery position for engagement of the straight portion of a groove 29 therein with roller 28, to retain chamber 26 in the six oclock firing station thereof as shown in Fig. 1. A cartridge 30 is shown in chamber 26v with an aperture. 32 in the base. thereof, and. a primer 33 recessed in the aperture.

A firing pin assembly 34 includes a cylindrical anvil 36 secured in pedestal 20 by a set screw 38 and a front plate 40 secured by press fit in anvil 36. Plate 40 includes a locating tab 42. A firing pin tip 44 and body 4'6, of electrically-conductive material, extend through separate carriage and crank ends 48 and 50, respectively, of a cylindrical clutch 52 rotatably disposed in pedestal 20 in axial alignment with chamber 26'. Ends 48 and 50 are provided with meshing teethshown at 54, Figs. 3

and 6, for concerted rotation about the axis of the firing pin.

Tip 44 and body 46 are provided with flanges 56 disposed within clutch 52 and a spring 58 is compressed for electrical connection between the tip and the body. Body 46 extends rearwardly from pedestal 20 and includes a terminal 60 for electric connection through a knife switch 61 disposed between actuator 18 and recoil unit 16 for battery position connection to the aboveground conductor of a grounded external supply source. Tip 44 and body 46, respectively, are inclosed in insulators 62 and- 64.

Front plate 40 is formed with a diametrical knife edge projection 66 extending rearwardly therefrom and carriage end 48 includes a corresponding groove 68 for engagement therewith when actuator 18 is in battery posi- Spring 58 and tip 44 are formed for electrical contact of the firing pin with primer 33 to conduct a current thereto when projection 66 is in engagement with groove 68. It is evident that. spring 58 compensates for the accumulation of tolerances in the dimensions locating primer 33 with respect to pedestal 20.

Actuator 18 operates in an indexing cycle to accelerate and decelerate rotation ofdrum 22 responsive to discharge of cartridge. 3.0 to replace chamber 26 in the firing position with a chamber 84. As shown in Fig. 4, chamber 84 is rotationally successive to chamber 26 in drum 22.

Crank end 50includes a projection 70 having a square end and projecting rearwardly from pedestal 20 for fixed engagement with one end of a link 72. A cross-head follower 74 slidable in a guide 75- in pedestal 20 includes actuator slides rearwardly, pin 76 engages portion 83 of cam 78 to rotate clutch 52, clockwise as seen in Fig. 4;

As clutch 52 rotates, projection 66 and groove 68 are disengaged to retract tip 44- against spring 58 and permit chamber 26 to be replaced'in the firing station with cham ber 84. In the return ofv actuator 18 to battery position, carriage end 48 is oppositely rotated responsive to cam 78 to permit projection 66 and groove 68' to reengage' and tip 44 to be again projected by Spring 58 to engagement with:

the primer of a cartridge in chamber 84.

As indicated by the above description, cam 78 is formed for Withdrawal of tip 44 from engagement of'a cartridge chambered in' the firing station and to permit return of tip 44 to such engagement while the straight portion of grove 29 engages the roller in the rearward and forward strokes of actuator 1'8, respectively. Firing pin tip 44, therefore, is withdrawn from the normal position earlier and returns to the normal position later than the firing pin described above to decrease the opportunity for stray electric currents to discharge the firing position cartridge.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

ing pin inthe recoil unit biased to a position of electrical.

contact with the cartridges chambered in the firing station for the discharge, and a reciprocal member disposed.

for rotation about .the axis of the weapon for positive displacement of said firing pin from said contact position and return of the firing pin thereto, responsive to the remaining portions. of the reciprocal operation.

2; In an electrically-fired automatic Weapon including a recoil unit, a drum with cartridge chambers and a firing station therefor, and an actuator for engagement with the drum biased to a battery position for selectively retaining the chambersin' the firing station for discharge of cartridges in the chambers and disposed for reciprocal operation responsive to the discharge and for rotation of the selected chambers from the firing station responsive to portions of the reciprocal operation, a firing device eng-ageable with the'actuat-or comprising an insulated firing pin in the recoil unit biased to a position of contact with the cartridges chambered in the firing station for the discharge, a knife edge'projection'in the recoil unit in diametral relation to said firing. pin, a circular disc having a groove corresponding to said knife edge for battery position engagement therewith, and; means for rotation of said disc from and to said knife edge engagement respectively to positively displace said firing pin from said contact position and to permit the firing. pin to be returned thereto, responsive to the remaining portions of the reciprocal operation.

3. In an' electrically-fired automatic weapon including a recoil unit, a drumwithzcartridge chambers and a firing station. therefor, and an actuator for engagement with the drum biased tov a battery position for selectively retaining the chambers in the firing station fordischarge of cartridges in the chambers and disposed for reciprocal operation responsive to the discharge and forv rotation. of the selected chambers from the firing. station respon- V sive to portions of the reciprocal operation, a firing device engageable with the actuator comprising an insulated firing pin in the recoil unitbia-sed to a position of contact with cartridgeschambered. inv the firing. station. for the discharge, a knife edge projection in the recoil unit disposed in diametral relation to said firing pin, a clutch including'a body endand acar-riageend in meshed relati-on therewith including a groove corresponding to. said References Cited in the file of this patent knife edge for battery position engagement therewith, UNITED STATES PATENTS and means for rotation of said 'body end for consequent rotation of said crank end from and to said knife edge 800,663 Meigs et 190s engagement to positively displace said firing pin from said 5 Melgs et 1906 contact position and to permit the firing pin to be re- 1087219 Dawson et 1914 turned thereto responsive to the remaining portions of FOREIGN PATENTS therecipmcawlerafim' 863,614 Germany Jan. 19, 1953 

